[sipcore] 答复: Re: New revision of the re-INVITE handling draft

[[e-mail]]

Hi Shinji,

By RFC3311, the target refresh UPDATE can refresh the ongoing Re-INVITE, 
as below: 

UPDATE is a target refresh request. As specified in RFC 3261 [1],
   this means that it can update the remote target of a dialog. If a UA
   uses an UPDATE request or response to modify the remote target while
   an INVITE transaction is in progress, and it is a UAS for that INVITE
   transaction, it MUST place the same value into the Contact header
   field of the 2xx to the INVITE that it placed into the UPDATE request
   or response.

And then, we can get the correct session state by the way proposed in 
draft-camarillo-sipcore-reinvite-00. 

Gao



>A difficult case is where a reINVITE has been initiated, and has not 
>completed. (Perhaps its ringing.) Then the UAC loses its IP address or 
>IP connectivity and needs to make a target change. So it sends an UPDATE 
>with the target change. What it should probably do in that case is *not* 
>include an offer in the UPDATE. Then it can't be rejected for o/a 
>reasons. Once that is done it can continue the o/a process, updating its 
>media addresses when it has the chance. Once the UAC target has changed, 
>the UAS should not fail the INVITE. If need be it should reject all the 
>media in order to avoid that.

At this point, IP Address of the UAC has be changed, so the
responce of the reINVITE request could probably not be returned
to the UAC. And then reINVITE client transaction would return
a timeout. Rather it would be better to CANCEL it.

Altogether UPDATE transaction SHOULD be excluded from the
rollback, I think now.


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